Electrode mounting arrangement



Jan. 28, 1941.

T. G. CRAWFORD 2,229,957

ELECTRODE MOUNTING ARRANGEMENT Filed sept. 19, 1940 Fig.

Inventor Thames G. Cravvovd,

His Attorney.

Patented Jan. 28, 1941 Y UNITED STATES PATENT oF/.FICE

ELECTRODE MOUNTING ARRANGEMENT Thomas G. Crawford, Glenville, N. Y., assignor to General Electric Company, a corporation of New York Application September 19, 1940, Serial No. 357,424

4 Claims. (Cl. Z50-27.5)

The present invention relates to an improved tate its assembly with a water jacket or other electrode mounting arrangement for electric dismeans for cooling the exterior anode surface. charge devices. While not limited thereto, the Within the anode and arranged coaxially thereinvention is especially applicable in connection with there is provided a separately heated cath- 5 with high frequency power tubes. ode comprising a plurality of filaments I3 which 5 Tubes of the character referred to generally are arranged in hollow configuration. These illemploy a cathode which is made up of a pluaments are in turn surrounded by a grid strucrality of separate elongated filaments positioned ture which is shown as comprising grid wires I5 in closely spaced relationship to other parts of wound helically on a plurality of stay rods I6 l0 the tube structure, such as the grid. With this which parallel the filaments i3. For high fre- 10 f arrangement there is a danger that short-circuitquency operation the grid is preferably arranged ing may occur as a consequence of uncompenvery close to the cathode structure so that the sated expansion of the cathode laments. This spacing between the grid Wires and the cathode danger has been found to be especially great in filaments may be on the order of 0.180 inch.

connection with tubesinwhich the cathode heat- The open end of the anode is hermetlcally 15 ing current is supplied to the various filaments joined to a glass envelope I1 which serves to seal from a polyphase source which is subject to unthe discharge space between the anode and balanced operation. Under these circumstances, cathode. The envelope is provided with an inthe individual laments may be heated to diiersulating base I9 which is held in place by means o ent degrees so that the resultant unequal expanof a flanged metal member 20 cemented to the 20 sion of the filaments tends to cause distortion of envelope. 'I'he base i9 'serves to support a sethe cathode structure and breakage of its parts. ries of terminal elements 22 which are respec- It is an object of the present invention to protively associated with lead-in conductors 23 for vide a cathode mounting which eliminates the the various cathode filaments. 'A duct 24 ex- ;5 expansion difliculties outlined in the foregoing. tending through the base serves as an inlet for a 25 In a broad sense, this is accomplished by providcooling fluid, such as air, which may be introing each of the cathode laments with a separate duced to maintain the end of the envelope at a tensioning assembly. It is considered, however, safe temperature. that the more important aspect of the invention Within the enclosure formed by the envelope Il :lo consists in a. particular form of assembly which there is provided a glass sleeve 26 which extends 30 assures satisfactory operation under extreme toward the anode I0 and to which there is seconditions and which permits the attainment of cured a flanged metal sleeve 2l. The sleeve 2l a long life under such conditions. serves as a mounting element for the grid struc- The features which I desire to protect herein ture which is secured thereto through the agency are pointed out with particularity in the appended of a second anged ring 28. This second ring is 35 claims. The invention itself, together with furconnected directly to extensions of the grid stay ther objects and advantages thereof, may best be rods I6 and is in clamped engagement with an understood by reference to the following descripannular disk member 30 to which a lead-in contion taken in connection with the drawing in ductor 3l for the grid is secured. The conductor which Fig. 1 is a longitudinal sectional view of 3| is provided with an externally accessible grid 40 an evacuated discharge device suitably embodyterminal 32. Concentric with the sleeve 26 there ing the invention; Fig. 2 is an enlarged detail is provided a reentrant circular press 35. This view of the cathode arrangement shown on a serves as a mount for a plurality of fixed termismaller scale in Fig. 1; Fig. 3 is a section taken nals 31 which are connected outside the envelope on line 3-3 of Fig. 2; and Fig. 4 is a sectional with the current supply conductors 23. The var- 45 view of one of the mounting element of Fig. 2, icus terminals 31 are supported in rigid assembly showing the same as it appears when the assoby means of an apertured metal disk 40 which ciated cathode filament is in fully expanded conembraces the various terminals but which is indition. sulated therefrom by a plurality of insulating Referring particularly to Fig. l there is shown sleeves 4I, suitably consisting of quartz. This 50 a discharge device comprising an elongated cylindisk also engages and serves as a partial support drical anode I0 which consists, for example, of for a xed rod 42 which forms the central stem of copper and which constitutes a portion of the the cathode structure and from which all the enclosure of the device. The anode is provided cathode filaments are supported at the end of with an outwardly extending flange Il to facilithe envelope which is remote from the stem 55 press 35. The supporting connection between the filaments and the rod 42 is made through a metal disk 43 which peripheraily engages the various maments. The filaments are held in contact with the disk 43 by being welded together at their extremities as indicated at 44. In the intended use of the device in connection with a multiphase cathode current supply, the point 44 represents the neutral point of the cathode so that no current connection for the rod 42 is required.

As appears most clearly in Fig. 2, each of the fixed terminals 31 is fitted with a metallic sleeve 46 which extends from the terminal toward the other extremity of the envelope. Each of the sleeves has in the end which is remote from its associated terminal an apertured disk 46' with an o `ing of sufficient size to receive loosely a mem er 4T constituting an extension of one of the cathode filaments. The members 41 are held in appropriately spaced relationship by means of insulating eyelets 48 which abut the extremities of the various sleeves and which engage the members with suiiicient clearance to permit their axial motion. The -eye1ets 48 are mounted on an apertured disk 49 which is secured centrally to the cathode rod 42.

As is illustrated by the sectional sleeve of Fig. 2, each of the filament extensions 41 terminates in a disk 50 which slidably engages the inner surface of the sleeve so as to be capable of longitudinal movement therein and which furnishes a guide for the member to which it is secured. A compression spring 5l arranged Within the sleeve 46 bears on the under surface of the disk 50 and thus serves to maintain the connected filament under tension. A flexible connection between the guiding disk and the fixed terminal 3l is provided by means of a number of helically formed braided conductors 53 which may suitably be constituted of copper. 'I'hese conductors are capable of considerable Vextensive and compressive movement so that an appreciable expansion of the cathode filaments may occur without danger of breaking the current supply path.

The operation of the cathode tensioning means is best shown in Fig. 4 which illustrates the condition of one of the springs 5l and the asso= ciated conductors 53 'when the ilarnent con nected therewith is in its fully expanded condition. It will be noted that under these cir curcstances, the various turns ci the conductor 53 have become closely compacted while the turns ci the spring 5i have opened due to their longitudinal expansion.

arrangement o?? the hind specified possesses theadvantage that it permits unequal expansive movements -oi the various cathode :filaments to occur without thereby causing any distortion or the cathode structure as a whole. As has been previously pointed out, this is a consideration which is especially important in cases where the various filaments of the cathode are to be supplied from a polyphase current source. In numerous instances a temporary unbalancing of the phase voltages of such a source may cause a serious discrepancy in the amount of heating of the various filaments and may thus cause certain iilaments to expand a great deal more than others. The arrangement described in the foregoing permits this action to occur without actually warping the cathode structure or disturbing the spatial relationship between the cathode filaments and the grid structure.

The particular arrangement specified, wherein each of the filament tensioning means is enclosed within a separate metallic sleeve, has the advantage that the various springs and exible conductors are well protected from heat generated within the discharge space and also from the occurrence oi' excessive heating during the exhaust procedures to which devices of the character under consideration are ordinarily subjected. Moreover, this arrangement provides a compact construction and one which may be relied upon to have a long operating life even under veryadverse conditions of operation.

While the invention has been described by reference to a particular embodiment thereof, it will be understood that numerous modifications may be made by those skilled in the art without departing from the invention. I therefore, aim to cover in the appended claims all such equivalent variations as come within the true spirit.

and scope of the foregoing disclosure.

What Iclaim as new and desire to secure by Letters Patent of the United States is:

l. An electric discharge device comprising an anode, a cathode consisting of a plurality of elongated iilaments, an envelope hermetically sealing the discharge space between the anode and cathode, a plurality of lead-in wires extending within the envelope and having fixed terminals therein, and a plurality of mountings for separately tensioning the various cathode iilaments, each said mounting including an elongated sleeve, means comprising an extension of one of the said filaments projecting into the sleeve so as to be longitudinaliy movable therein, a. compression spring within the sleeve and acting to maintain the said iilament under tension, and a conductor also within the said sleeve and providing a flexible connection between the said filament extension and one of the said iixed lead-in terminals.

2. Anelectric discharge device comprising an (anode, a cathode consisting of a plurality of elongated filaments, an envelope hermetically sealing the discharge space between the anode and cathode, a plurality o! lead-in wires extending within the envelope and having iixed terminels therein, and a plurality of mountings for separately tensioning 'the various cathode zla niente, each said mounting including an elongated-sleeve connected with and forming an ex" tension of one of the said lead-in terminals, P com; an extension of one said fila .ents projectimg into said sleeve at the end ther-eci which is remote from the said lead-in tern mined, Within the said sleeve and 'tendto move the said filament extension toward the said terminal se as to maintain the lament under tension, and a conductor within. the sleeve providing e. flexible connection between the filament extension and the said lead-in terminal.

3. An electric discharge device comprising an anode, a cathode consisting of a plurality of elongated iilaments, an envelope hermetically sealing the discharge space between the anode and cathode, a plurality of lead-in wires extending Within the envelope and having terminals therein, and a plurality of mountings for separately tensioning the various cathode iilaments, each said mounting including an elongated sleeve connecting at one end with one of the said terminals, means comprising an extension of one of the said laments projecting into the sleeve atthe end thereof which is remote from the said terminal, means slidablyengaging the interior of the said sleeve for guiding the motion of the said iilament extension thereimaspringwithinthesie'eveiorurdngthe said filament extension towardthe saidterminal soastomaintainthenlunentundertensiomand a readily deformable conductor extending longitudinmlly of the said sleeve between the iilxinieni;V extension and the lead-in terminal for provid` Y ing a ilexible connection between them.

Y 4. An electric discharge device comprising an anode. a cathode consisting of a plurality of elongated maments, an envelope hermetically seeling the discharge space between the anode and necungatoneendwlthoneoftnsaxdrmmms, means comprising an extension of one 'of the said maments projecting into the sleeve at the end thereof which is remote from the said ter-` minai. means slidahly the interior of the said sleeve for guiding the motion of the said iiiament extension therein, a spring within the sleeve for urging the saidl iilament extension towardthesaidterminalsoastomaintainthe iilament under tension, and a helically formed braided conductor within the said sleeve for providing a exible connection between the said lilament extdision and one of the said ixed lead-in THOMAS G. 

